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Respiratory system and its mechanisms :

Respiratory system and mechanism contents :

Respiratory system and mechanism contents Introduction on respiratory system
Upper respiratory tract
Bronchial tree
Bronchopulmonary segments
Muscles of respiration
Movement of chest wall
Surface anatomy of the lungs Mechanics of rspiation
Lung volumes
Compliance of the lungs and chest wall
Work of breathing
Postural relationship
Applied part

Introduction respiratory system :

Introduction respiratory system Respiratory system extracts oxygen from the atmosphere , and the body utilizes the oxygen and produce CO2as a result of metabolism

The Respiratory System :

The Respiratory System Basic functions of the respiratory system
Breathing (Pulmonary Ventilation) – movement of air in and out of the lungs
Inhalation (inspiration) draws gases into the lungs.
Exhalation (expiration) forces gases out of the lungs.
Non –pulmonary functions:
Gas Conditioning – as gases pass through the nasal cavity and paransal sinuses, inhaled air becomes turbulent. The gases in the air are
• warmed to body temperature
• humidified
• cleaned of particulate matter
Protects respiratory surfaces
Site for olfactory sensation
Secretes pulmonary alveolar macrophages
Functions of pulmonary circulation
Endocrine functions .

Respiration processes :

Respiration processes Respiration – four distinct processes must happen
Pulmonary ventilation – moving air into and out of the lungs
External respiration – gas exchange between the lungs and the blood
Transport – transport of oxygen and carbon dioxide between the lungs and tissues
Internal respiration – gas exchange between systemic blood vessels and tissues

The Paranasal Sinuses :

The Paranasal Sinuses Figure 7.11a, b

The Pharynx :

The Pharynx Funnel-shaped passageway
Connects nasal cavity and mouth
Shared by the digestive and respiratory systems
Divided into three sections by location
Nasopharynx – superior portion,
Oropharynx – continuous with the oral cavity
Laryngopharynx – between the hyoid bone and the esophagus

The Nasopharynx :

The Nasopharynx Superior to the point where food enters
Only an air passageway
Closed off during swallowing
Epithelium consists of ciliated pseudostratified epithelium that moves mucus

The Oropharynx :

The Oropharynx Arch-like entranceway – fauces
Extends from soft palate to the epiglottis
Epithelium - stratified squamous epithelium
Two types of tonsils in the oropharynx
Palatine tonsils – in the lateral walls of the fauces
Lingual tonsils – covers the posterior surface of the tongue

The Laryngopharynx :

The Laryngopharynx Passageway for both food and air
Epithelium - stratified squamous epithelium
Continuous with the esophagus and larynx

The Larynx :

The Larynx Prevent food and drink from entering the trachea
Passageway for air
Produces Sound
It connects the pharynx to the trachea
Epithelium of the larynx
Stratified squamous – superior portion
Pseudostratified ciliated columnar – inferior portion

The Larynx :

The Larynx Vocal ligaments of the larynx
Vocal folds (true vocal cords) - act in sound production
Vestibular folds (false vocal cords) - no role in sound production
Voice production
Length of the vocal folds changes with pitch
Loudness depends on the force of air across the vocal folds

The Trachea :

The Trachea :

The Trachea Figure 21.7a, b

Bronchi in the Conducting Zone :

Bronchi in the Conducting Zone Bronchial tree - extensively branching respiratory passageways
Primary bronchi (main bronchi)
Largest bronchi
Right main bronchi - wider and shorter than the left
Secondary (lobar) bronchi
Three on the right
Two on the left
Tertiary (segmental) bronchi - branch into each lung segment
Bronchioles - little bronchi, less than 1 mm in diameter
Terminal bronchioles - less than 0.5 mm in diameter

Lobes and Surfaces of the lungs :

Lobes and Surfaces of the lungs Right lung has three lobes
Left lung has two lobes
Concavity on medial surface = cardiac notch
Bronchi enter the lungs at the hilus

movement of inspiration :

Pump handle movement :

Pump handle movement Quiet respiration- only first pair of ribs moves but little .
On hypernoea .the 2nd and 6th ribs which slopes obliquely downwards and forwards from their joints with the spinal column , moves upwards to assume a more horizontal position due to contraction of the external internal costal muscles
Increases in the anterior- posterior diameter of the thorax
Also the curves of the ribs increases in transverse diameter

Bucket handle movement :

Bucket handle movement This movements brings about the increase in transverse diameter of the thorax by the movement of the lower 7th to 10 rib which swings outward and upwards

Diaphragmatic movements :

Diaphragmatic movements During inspiration , diaphragm contracts and draw the central tendon part downwards by 1.5cm in eupnoe and 7cm in deep respiration …
Cause an increase in transverse diameter of the thorax
Accounts for 75% of the tidal volume

Expiration or exalation :

Expiration or exalation Lots of elastic tissue in lungs and thoracic wall
It’s a passive process
Recoil helps return tissues to original configuration
Alveoli enlarge during inspiration, contract during expiration

Here is an experiment :

Here is an experiment

Mechanism of pulmonary ventilation :

Mechanism of pulmonary ventilation

The respiratory muscles :

The respiratory muscles

Biomechanics of breathing :

Biomechanics of breathing During tidal breathing , if unopposed by the scalenes and the parasternals , the negative pleural pressure and the rsultant decreased intrapulmonary pressure are strong enpugh to cause the upper chest to collapse inward during inspiration .
During diaphragmatic contraction , the abdomen becomes the fulcrum to lift the lower rib cage and rotate it outward .

Mechanisms of breathing :

Air movement :

Air movement Movement of air depends upon
Boyle’s Law
Pressure and volume inverse relationship
Volume depends on movement of diaphragm and ribs
Pressure and airflow to the lungs

Pressure changes during inhalation and exhalation :

Pressure changes during inhalation and exhalation Relationship between intrapulmonary pressure and atmospheric pressure determines direction of air flow
In quiet breathing , at end expiration and at end inspiration .no air is going in and out of the lungs as the intrapulmonary pressure and atmospjeric pressure are equal.
Intrapleural pressure maintains pull on lungs
Pressure in the space between parietal and visceral pleura. Causes a slight change in the subatmospheric pressure i.e. -2mmhg at the start of inspiration . This is proportuonal to the thorarcic expasion

Respiratory volumes :

Respiratory volumes Alveolar volume
Amount of air reaching the alveoli each minute
Tidal Volume (VT)
Amount of air inhaled or exhaled with each breath
Vital capacity
Tidal volume plus expiratory and inspiratory reserve volumes
Residual volume
Air left in lungs after maximum exhalation

Respiratory volumes and capacities :

Respiratory volumes and capacities

Diffusion and respiratory function :

Diffusion and respiratory function Gas exchange across respiratory membrane is efficient due to:
Differences in partial pressure
Small diffusion distance
Lipid-soluble gases
Large surface area of all alveoli
Coordination of blood flow and airflow

An overview of respiratory process and partial pressure :

An overview of respiratory process and partial pressure

Compliance :

Compliance compliance is the change in lung volume per unit change in airway pressure , which gives the distensibility or stechability of the lungs and chest wall.
Expressed as litre/cm h2o
Studied in two ways – compliance of the lungs and chest wall
and compliance of the lungs only

Compliance of the lungs and chest :

Compliance of the lungs and chest It is o.13cm/H2O .i.e. when there is increase of pressure by 1cm H2O the volume of the lungs inside the thoracic wall increases by 0.13 cm/H2O

COMPLIANCE OF THE LUNGS ALONE :

COMPLIANCE OF THE LUNGS ALONE ie lungs outside the chest wall
Compliance 0.22 litre cm/H2O.ie when the airway is increase by 1cm H2O,then the lungs expand by 0.22 lt
Therefore compliance of the lungs alone is approx 2times the compliance of the lung and chest wall.this is so because inside the thorax some energy is required to expand the thorax also.

Respiratory centres and the brain :

Respiratory Centers and Reflex Controls :

Figure 23.27 Respiratory Centers and Reflex Controls

Slide 59:

Effects of Posture
Abdominal Pressure Breathing

Postural relationship :

Postural relationship The height of the diaphragm varies in the thorax to the position of the body and tone of the abdominal muscles .
Sitting – here the diaphragm is the lowest , due to gravity and not press on the abdominal contents ,so less effort in inspiration,and RV is increase .most comfortable .
Standing- the diaphragm is mid-way
Supine – the diaphragm lies in the highest position , uncomfortable position

In dysponea :

In dysponea So the comfortable position is sitting up which allows maximum ventilation, by leaning forwards and fixing the arms ,this fixes the scapulae, so that the serratus anterior and pectoralis minor may act on the ribs ,thus aidind for respiration.

Transection of the spinal cord :

Transection of the spinal cord Above the 3rd cervical segment – fatal without artificial respiration
Below the 5th not fatal as the phrenic nerves(c3,4,5) is intact.
Paralysis of the laryngeal nerve supplying the intrinsic muscles of the larynx cause inspiratory stridor .

applied :

applied During pregnancy at the second half of the pregnancy there is progressive uterine distension repositioning the diaphragm cephalad with a resultant increased in in chest circumferance.
Scoliosis affects the chest wall biomechanics causing limititation to ventilation-how?
on side of the convexity the along with the transverse process the ribs moves – causing posterior rib hump- the intercostal space are widened up , wheras on the concavity side the intercostal spaces are narrowed.
This leads to insufficiency of the intercostal muscles and other ventilatory muscles – reduces chest wall compluance – decrease lung functions

Chronic obstructive pulmonary disease :

Chronic obstructive pulmonary disease Hyperinflation of the lungs due to destruction of the alveolar walls -_so elastic coiling of the lung is lessened_so at the end of tyche exalation more air is housed_ assumes position of end inspiratory cycle – thorax becomes barrel shaped _also diaphragm gets flattened(expiration diaphragm dome shaped)_pulls the lower ribs inwards working against inflation
In copd inspiration is carried out by acessory muscles.ie parasternals ansd scalenes

Paradoxical breathing in copd :

Paradoxical breathing in copd So in COPD the upper ribs is pulled upward and outward and as the diaphragm has limited efficiency to push the abdominal contents downward , so the abdominal and diaphragm moves upward , under the rib cage .this is paradoxical thoracoabdominal breathing (the abdomen is pulled inward and upward during inspiration and is pushed outward and downward during expiration).